Circuit breaker apparatus having bifurcated contact



June 6, 1967 3. H. LACAN 3,324,270

CIRCUIT BREAKER APPARATUS HAVING BIFURCATED CONTACT Filed July 25, 1966 United States Patent 3,324,270 CIRiJUIT BREAKER APPARATUS HAVING BIFURCATEH) CONTACT Guy Henri Lacan, Carriere-sous-Bois, France, assignor to La Teiernecanique Electrique, Nanterre, Seine, France, a corporation of France Filed July 25, 1966, Ser. No. 567,508 Claims priority, application France, Aug. 3, 1965,

10 Claims. ((31. 200166) The co-pending application No. 464,287 describes contact poles to be used in pairs, each pole comprising one arm and one flat contact block in relief on this arm.

The characteristic features of the pole are that the arm and the block carried by that arm are divided into two by a central slit, this slit having a progressive and symmetric enlargement towards the current junction of the pole. The two sections of the arm which carry the halfblocks are flat, and extend at least to the said enlargement. In the closed position of the pairs of poles, being parallel and orientated in the same direction, the sections of each half arm, at the level of the said enlargement, are reduced with respect to the sections of these half arms beyond the enlargement. The mean line of passage of the current in these reduced sections is further from the said central slit than from the outer edge of the corresponding half-blocks.

Thus, as explained in the co-pending application No. 464,287, when the contacts separate from one another the electric are appearing between the blocks is displaced spontaneously and without any intervention from any pneumatic, magnetic or electromagnetic extinguishing device, both towards the longitudinal axis of the pole, that is towards its central slit, and towards the free end of this pole, which is arranged as extinction horn for the arc.

According to the present invention, there is provided an improvement in or modification of the switching or circuit-breaker device described in the specification Ser. No. 464,287 in which at least one moving contact bridge bar with at least two moving opposing poles co-operates with at least two symmetrical fixed poles, the fixed poles being formed into a U-shape, with the curved portions of the poles opposing each'other in the plane of displacement of the moving bar, the opposing parts of the bar and the fixed poles being parallel, slit longitudinally and supporting split contact blocks, the slits being enlarged towards the current input position to provide portions with reduced sections in the bar and the fixed poles such that the mean line of the current is spaced at a greater distance from the longitudinal axis of the bar or fixed pole respectively than from the lateral outer edge of the split contact block.

Thus for the two bridge contacts the mean lines of the current form two loops, the curvatures of which are opposed and directed outwards, each of them being similar to the loop formed by such a line in the co-pending application No. 464,287.

In a preferred embodiment of the invention, the poles constituting the fixed contacts are bent into a U in the region of the enlargement in the slit, and the pole is fixed to its support immediately beyond the said enlargement.

Thus, given that the active part of the pole producing the auto-extinguishing eifect is that between the split contact block and the point where the enlargement is greatest, with such an arrangement, despite the curvature of the pole, the whole of its length is active in achieving the desired efiect.

One of the advantages achieved with these types of arrangement for devices for double current cut-off is the following: the pairs of poles achieving the auto-extinguishing effect are clearly more effective for large currents than small ones. However, a given cut-off device might have to cut off both large currents and small currents the latter sometimes in repeated sequence. Operating two cutofi's in series by means of poles formed in accordance with the above identified patent application makes it possible to conserve the advantages of auto-extinction whilst diminishing the wear on the cont-acts when cutting off weak currents. This wear is due to the low efliciency of the auto-extinction, and is reduced by accelerating the opening of the contacts. It will be remembered that the principal advantage of double cut-oft is the following: an increase in the limiting cut-01f intensity because the tension for re-establishing the arc is divided into two. The overall limiting intensity therefore is increased to more than twice that possible with a single cut-off of the same length.

The invention can also be applied to certain difiicult conditions for cut-oft, for example with high voltages or alternating current with a high frequency intended for heating by induction. The invention which is the object of the above identified patent application can thus be applied over a wide field, since cut-off devices with the so-called bridge contacts are supplied for all sorts of sources of energy, and are in general use.

A cut-off device incorporating embodiments of the invention will now be described in greater detail with reference to the accompanying drawings, of which:

FIG. 1 is a schematic cross-section through a relay or contactor device operating two bridge contacts,

FIG. 2 is a section along line II-II in FIG. 1, and,

FIGS. 3, 4 and 5 are perspective views of the moving contact, the fixed contacts and a variant of the fixed contact.

The apparatus shown in FIG. 1 comprises an electromagnetic coil 1 acting on an armature 2, integral with a mobile assembly 3, the armature being subjected by the intermediary of this mobile assembly to the action of the return spring 4. The mobile assembly 3 is an insulator and, by means of a cylindrical or swivel joint 5, carries a bar for the moving bridge contact 6. A contact compres sion spring 7 acts on each bar.

The vertical motion of the moving assembly 3 is guided by guides, such as 8, arranged in the sides 91 (or intermediate walls 10 in the case of multi-pole apparatus comprising a number of bars 6). These sides and walls are integral with the two halves of the box 11 of the apparatus. The box 11 carries the input and output terminals 12 for the current, supporting the fixed cut-off poles 13 assembled with these terminals and with the box 11 by the screws 14.

Grooves in the sides 9 and walls 10 hold the sheets 15, the purpose of which is to favour extinction of the are by fragmenting it in a known manner. The are extinction chambers are enclosed by the walls 16, 17 and 18 which, depending on convenience of construction, can be either integral with one another or integral with the box 11, or again integral with the sides 9 and intermediate walls 10.

In this embodiment the assembly 3 carrying the moving contact or contacts forms an insulating partition 30 which extends between the fixed contact poles and separates them, in addition, these partitions can have ribs 20 engaging in the enlarged portion of the slit in the contacts to separate the two parts of the fixed poles.

Each of the two ends of a bar 6 has a central slit 21 which has a V shaped enlargement towards the centre of the bar; on either side of the central slit there are halfblocks 23. The central part 24 of the bar 6 is solid and is not split, so that it can rest on the moving assembly 3 and support the pressure of the spring 7.

This central part should have an area just sufficient to serve these purposes since, from the point of view of lightness and the amount of space occupied, the length of the moving contact bars should be reduced as much as possible. The bars 6 are formed by cutting and bending into a U a conducting sheet of such dimensions that the mean line of the current passing through section S which is diminished by the enlargement in the slit, is further from the axis of the central slit 21, than the distance from the edge 23a of the corresponding halfblock 23 to that axis.

The fixed contact poles 13 are also obtained by forming a sheet into a U in the transverse'direction and then bending the sheet treated in this Way into a U shape. Preferably the U bends are made at the point where the enlargement 25 in the central slit 26 is largest. Thus the mean lines of the current passing through the reduced sections S can still be directed towards the central slit 26, the mean lines being further from the axis of this slit than the lateral edge 27a of the corresponding half block 27.

As the means 14 for fixing each fixed pole is inserted in the solid part of the fixed pole just beyond the enlargement 25, the whole length of the fixed pole is effective in the auto-extinction; furthermore bending the pole into a U in this way where the enlargement is largest makes it possible to bring the two fixed poles nearer together, that is to shorten the bar 6.

The poles end in arc extinction horns, these horns, at least for one of the poles, are preferably deflected in the direction opposite to that of the plane of contact so as to ensure that the foot of the arc fades even when the contact blocks are very worn.

As shown in FIG. 5, the central slit 26 of a pole 13a can be enlarged, for example in the manner indicated by 28, beyond the blocks 27 in the direction in which the arc recedes towards the point of the horn to avoid any risk of this are passing from one of these half-poles to the other.

Obviously the embodiments which have just been described can be modified without going beyond the scope of the present invention, in particular by the substitution of mechanical equivalents.

I claim:

1. A switching or circuit-breaker device comprising in combination a moving-contact bridge bar bifurcated at both ends thereof, having contact pole blocks secured at the extremities of all four arms, and a pair of symmetrical poles formed into a pair of U-shapes, a sta tionary support member carrying the poles, their curved portions being opposed to one another, the free sides of the poles being split longitudinally, the slits being enlarged towards the opposing curved portions, the free sides each carrying a pair of contact blocks on their outer sides, the enlarged portion of the slit being adapted and arranged to provide remaining portions of the contact poles on both sides of the slits which have their mid points at a greater distance from the longitudinal axis of the moving-contact bridge bar than from the lateral outer edges of their respective fixed contact blocks.

2. A switching or circuit-breaker device as claimed in claim 1 in which the enlargements of the slits are symmetrical.

3. A switching or circuit breaker device as claimed in claim 1 in which the enlargements of the slits on the stationary contact poles are a maximum in the curved portions of the poles.

4. A switching or circuit-breaker device as claimed in claim 2 in which the enlargements of the slits on the stationary contact poles are a maximum in the curved portions of the poles.

5. A switching or circuit-breaker device as claimed in claim 1 in which the moving-contact bridge 'bar is supported on a partition separating the fixed contact poles.

6. A switching or circuit-breaker device as claimed in claim 2 in which the moving-contact bridge bar is supported on a partition separating the fixed contact poles.

7. A switching or circuit-breaker device as claimed in claim 3 in which the moving-contact bridge bar is supported on a partition separating the fixed contact poles.

8. A switching or circuit-breaker device as claimed in claim 4 in which the moving-contact bridge bar is supported on a partition separating the fixed contact poles.

9. A switching or circuit-breaker device as claimed in claim 7 in which each of the faces of the partition opposite the fixed poles has a rib partially engaging in the enlarged central slit of the fixed poles.

10. A switching or circuit-breaker device as claimed in claim 8 in which each of the faces of the partition opposite the fixed poles has a rib partially engaging in the enlarged central slit of the fixed poles.

References Cited UNITED STATES PATENTS 8/1965 Lemke 200l66 9/1966 Lawrence 200-166 

1. A SWITCHING OR CIRCUIT-BREAKER DEVICE COMPRISING IN COMBINATION A MOVING-CONTACT BRIDGE BAR BIFURCATED AT BOTH ENDS THEREOF, HAVING CONTACT POLE BLOCKS SECURED AT THE EXTREMITIES OF ALL FOUR ARMS, AND A PAIR OF SYMMETRICAL POLES FORMED INTO A PIAR OF U-SHAPES, A STATIONARY SUPPORT MEMBER CARRYING THE POLES, THEIR CURVED PORTIONS BEING OPPOSED TO ONE ANOTHER, THE FREE SIDES OF THE POLES BEING SPLIT LONGITUDINALLY, THE SLITS BEING ENLARGED TOWARDS THE OPPOSING CURVED PORTIONS, THE FREE SIDES EACH CARRYING A PAIR OF CONTACT BLOCKS ON THEIR OUTER SIDES, THE ENLARGED PORTION OF THE SLIT BEING ADAPTED AND ARRANGED TO PROVIDE REMAINING PORTIONS OF THE CONTACT POLES ON BOTH SIDES OF THE SLITS WHICH HAVE THEIR MID POINTS AT A GREATER DISTANCE FROM THE LONGITUDINAL AXIS OF THE MOVING-CONTACT BRIDGE BAR THAN FROM THE LATERAL OUTER EDGES OF THEIR RESPECTIVE FIXED CONTACT BLOCKS. 